Flow chart illustrating the equilibration and simulation phase. The disc properties are initialised according to the power laws in Eqs. (1) and (2). During the equilibration process (taking 26 kyr, equivalent to 274 orbits at the initial location of the inner planet) where the disc begins to “feel” the planets, the density profile changes significantly; see the first panel of Fig. 1 for the difference, where the equilibrated profile is shown as the dashed blue line.